After switching to a new version of phpBB I found out there are a few differences. One of them is I don't know to edit style directly via the admin interface. I need to make some small changes like to add google analytics code or change image in the style.
In the previous version I was able to open bookmark Style and edit template directly. Is there any way to do the same in the new version?
With the new versions is not possible.
The ability to edit styles in the ACP was removed from version 3.1.0. You would have to download the file, edit it and upload it via FTP and then purge the cache in ACP, General tab.
Source: https://www.phpbb.com/community/viewtopic.php?f=466&t=2270701